The computer and computer related industries have benefitted from a rapidly increasing availability of data processing functions. Along with this benefit comes the problem of how to present the great number and variety of available functions to the interactive operator or user in display interfaces that are relatively easy to use. In recent years, the hierarchal tree has been a widely used expedient for helping the user to keep track of and organize the operative and available functions. In typical tree structures, such as those in Microsoft Windows 2000™ and IBM Lotus™ systems, there is presented on the display screen a variety of operating and available functions and resources in tree hierarchies with classes and subclasses, or categories and lower categories of functions and resources displayed as objects or items at nodes in a descending and widening order based upon some kind of derivation from the next higher class or category. In conventional tree displays, as in the Lotus systems, it is customary to refer to categories in the hierarchical tree as being either in an expanded or collapsed state, i.e. an expanded or collapsed category. When a category is collapsed, it is at the lowest level of its particular hierarchical chain in the displayed tree. On the other hand, when a category is expanded, it is expanded into a list or set of displayed next lower level items, which, in turn, may respectively be the lowest level items in the tree or such items may also be collapsed but expandable categories. Such hierarchical trees of collapsed and expandable categories are considered in detail in the text, Lotus Notes 4 Plain and Simple, Rupert Clayton, published 1996, by Sybex Inc., Alameda, Calif., and particularly at pp. 235 through 236 and 144 through 146. Other systems may use other names to describe the order of classes and items in the hierarchical tree, such as classes and subclasses or parent and child elements, objects or items, but the processes and attendant problems in interfacing with such trees, which will be considered in the invention, will be similar. In the Lotus system, a variable symbol called a “Twistie” is used to designate whether a particular category or class is expanded. The Twistie symbol is a small triangle or arrowhead. When the Twistie is pointing horizontally, then its associated category is collapsed i.e. unexpanded. When the Twistie is pointing down, then the category is expanded to the list of items extending downward from the expanded category. Twisties are described in the above-referenced Lotus Notes 4 Plain and Simple text at po, 135 and 144. While the Twistie will be used in subsequently described embodiments of this invention, it should be noted that other expedients are used in this technology to designate an expanded category, e.g. highlighting or underlining.
With the many expanded functions handled through conventional computer desktop Graphical User Interfaces (GUIs), the windows through which the user may access and display the hierarchical tree of categories is often quite small. However, even if the user can conveniently expand the window to the full screen, a great many hierarchical trees are so extensive that the full tree is rarely completely displayable. This is particularly true with the smaller notebook and palm-type personal digital assistant computer displays.
Thus, windows in which only a small portion of the hierarchical tree is visible present problems to users. One significant problem is that the expanded categories that are hidden or no longer visible within the window because of the expansion to an extensive list of items and/or general user scrolling. When a user is relating to and considering alternatives for a particular item of interest, it is often important for the user to have a sense or a view of the hierarchical chain of an item or a list of items resulting from an expansion of a category. By hierarchical chain is meant the visualization of the links or category nodes back to a highest order or root category.
Currently, this may require a great amount of scrolling back and forth within the window to orient the user seeking hidden expanded categories and relating such categories to the listed items of interest. Such scrolling within small windows is particularly difficult and frustrating to users with physical and visual limitations.